But just as he who called you is holy, so be holy in all you do; for it is written: "Be holy, because I am holy." (NIV)
But as he which hath called you is holy, so be ye holy in all manner of conversation; Because it is written, Be ye holy; for I am holy. (KJV)
but like the Holy One who called you, be holy yourselves also in all your behavior; because it is written, "YOU SHALL BE HOLY, FOR I AM HOLY." (NASB)
1 Peter 1:15-16
Commentary
Holiness essentially defines the Christian's new nature and conduct in contrast with his pre-salvation lifestyle. The reason for practicing a holy manner of living is that Christians are associated with the holy God and must treat Him and His Word with respect and reverence. We therefore glorify Him best by being like Him (see vv. 16,17; Matt. 5:48; Eph. 5:1; cf. Lev. 11:44,45; 18:30; 19:2; 20:7; 21:6-8).
MacArthur, John Jr: The MacArthur Study Bible. electronic ed. Nashville : Word Pub., 1997, c1997, S. 1 Pe 1:15
Word Study
The Hebrew word for "holy" denotes that which is "sanctified" or "set apart" for divine service.
Youngblood, Ronald F. ; Bruce, F. F. ; Harrison, R. K. ; Thomas Nelson Publishers: Nelson's New Illustrated Bible Dictionary. Nashville : T. Nelson, 1995